Thermally assisted magnetic head, head gimbal assembly, and hard disk drive

ABSTRACT

A thermally assisted magnetic head comprises: a slider substrate, a first surface located opposite to a medium-facing surface, and side surfaces located between the medium-facing surface and the first surface; a magnetic head portion having a near-field light generator on the medium-facing surface side, and a magnetic recording element, the magnetic head portion being fixed to one of the side surfaces; and a laser diode element a relative position of which to the slider substrate is fixed so that emitted light thereof can reach the near-field light generator; a relation of λin&lt;λmax is satisfied, where λin is a wavelength of the emitted light from the laser diode element immediately before the emitted light reaches the near-field light generator, and λmax is a wavelength of irradiating light at which an efficiency of generation of near-field light generated from the near-field light generator is maximum.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermally assisted magnetic head forwriting of signals by thermally assisted magnetic recording and to ahead gimbal assembly (HGA) with this thermally assisted magnetic head,and a hard disk drive with this HGA.

2. Related Background of the Invention

As the recording density of the hard disk drive increases, furtherimprovement is demanded in the performance of the thin film magnetichead. The thin film magnetic head commonly used is a composite type thinfilm magnetic head of a structure in which a magnetic detecting elementsuch as a magneto-resistive (MR) effect element and a magnetic recordingelement such as an electromagnetic coil element are stacked, and theseelements are used to read and write data signals from and into amagnetic disk as a magnetic recording medium.

In general, the magnetic recording medium is a kind of a discontinuousbody of fine magnetic particles aggregated, and each of the finemagnetic particles is made in a single magnetic domain structure. Arecording bit is composed of a plurality of fine magnetic particles.Therefore, in order to increase the recording density, it is necessaryto decrease the size of the fine magnetic particles and thereby decreaseunevenness at borders of recording bits. However, the decrease in thesize of the fine magnetic particles raises the problem of degradation ofthermostability of magnetization due to decrease of volume.

A measure of the thermostability of magnetization is given byK_(U)V/k_(B)T. In this case, K_(U) represents the magnetic anisotropyenergy of the fine magnetic particles, V the volume of one magneticparticle, k_(B) the Boltzmann constant, and T absolute temperature. Thedecrease in the size of fine magnetic particles is nothing but decreasein V, and, without any countermeasures, the decrease in V will lead todecrease of K_(U)V/k_(B)T and degradation of the thermostability. Aconceivable countermeasure to this problem is to increase K_(U) at thesame time, but this increase of K_(U) will lead to increase in thecoercive force of the recording medium. In contrast to it, the intensityof the writing magnetic field by the magnetic head is virtuallydetermined by the saturation magnetic flux density of a soft magneticmaterial making the magnetic poles in the head. Therefore, the writingbecomes infeasible if the coercive force exceeds a tolerance determinedfrom this limit of writing magnetic field intensity.

As a method of solving this problem of thermostability of magnetizationthere is the following proposal of so-called thermally assisted magneticrecording: while a magnetic material with large K_(U) is used, heat isapplied to the recording medium immediately before application of thewriting magnetic field, to decrease the coercive force, and writing isperformed in that state. This recording is generally classified undermagnetic dominant recording and optical dominant recording. In themagnetic dominant recording, the dominant of writing is anelectromagnetic coil element and the radiation diameter of light islarger than the track width (recording width). On the other hand, in theoptical dominant recording, the dominant of writing is a light radiatingportion and the radiation diameter of light is approximately equal tothe track width (recording width). Namely, the magnetic field determinesthe spatial resolution in the magnetic dominant recording, whereas thelight determines the spatial resolution in the optical dominantrecording.

Patent Documents (International Publication WO92/02931 (JP-A 6-500194),International Publication WO98/09284 (JP-A 2002-511176), Japanese PatentApplication Laid-Open No. 10-162444, International PublicationWO99/53482 (JP-A 2002-512725), Japanese Patent Application Laid-Open No.2000-173093, Japanese Patent Application Laid-Open No. 2002-298302,Japanese Patent Application Laid-Open No. 2001-255254) and Non-patentDocument (Shintaro Miyanishi et al., “Near-field Assisted MagneticRecording” IEEE TRANSACTIONS ON MAGNETICS, 2005, Vol. 41, No. 10, p.2817-2821) disclose the thermally assisted magnetic head recordingapparatus of this type, in the structure in which a light source such asa semiconductor laser is located at a position apart from a slider witha magnetic recording element for generating a magnetic field and inwhich light from this light source is guided through an optical fiber, alens, etc. to a medium-facing surface of the slider.

Furthermore, Patent Documents (Japanese Patent Application Laid-Open No.2001-283404, Japanese Patent Application Laid-Open No. 2001-325756,Japanese Patent Application Laid-Open No. 2004-158067, Japanese PatentApplication Laid-Open No. 2004-303299) and Non-patent Document (KeijiShono and Mitsumasa Oshiki “Status and Problems of Thermally AssistedMagnetic Recording” Journal of the Magnetics Society of Japan, 2005,Vol. 29, No. 1, p. 5-13) disclose the thermally assisted magnetic headin which the magnetic recording element and the light source areintegrated on a side surface of the slider, and the thermally assistedmagnetic head in which the magnetic recording element and the lightsource are integrated on the medium-facing surface of the slider.

Studies have also been conducted on the magnetic heads using SIL (SolidImmersion Lens) being a high-efficiency condenser element or a plasmonprobe being a near-field light generating element. Patent Document (U.S.Pat. No. 6,795,630) discloses an apparatus with the plasmon probe at thetip of a planar waveguide.

SUMMARY OF THE INVENTION

However, the temperature of the laser diode element (semiconductor laserelement) being the light source rises during the recording operation ofthe thermally assisted magnetic head. It is known that the laser diodeelement decreases the intensity of emitted light with increase in thetemperature of the element. The decrease in the intensity of the emittedlight leads to insufficient heating of the recording medium and, inturn, insufficient reduction of coercivity, thereby causing writingfailure.

For preventing such failure, it can be contemplated that a temperaturedetecting element is disposed near the laser diode element and itsdetection result is fed back to a power supply unit of the laser diodeelement so as to keep the intensity of the emitted light constant.However, this method, if employed, will complicate the structure of thethermally assisted magnetic head and increase production cost.

The present invention has been accomplished in view of this problem, andan object of the present invention is to provide a thermally assistedmagnetic head capable of preventing the insufficient heating of therecording medium due to the rise in temperature of the laser diodeelement, in a simple structure, an HGA with this thermally assistedmagnetic head, and a hard disk drive with this HGA.

A thermally assisted magnetic head according to the present invention isa thermally assisted magnetic head comprising: a slider substrate havinga medium-facing surface, a first surface located opposite to themedium-facing surface, and side surfaces located between themedium-facing surface and the first surface; a magnetic head portionhaving a near-field light generator on the medium-facing surface side,and a magnetic recording element located in proximity to the near-fieldlight generator, the magnetic head portion being fixed to one of theside surfaces of the slider substrate; and a laser diode element arelative position of which to the slider substrate is fixed so thatemitted light thereof can reach the near-field light generator; whereina relation of λin<λmax is satisfied, where λin is a wavelength of theemitted light from the laser diode element immediately before theemitted light reaches the near-field light generator, and λmax is awavelength of irradiating light at which an efficiency of generation ofnear-field light generated from the near-field light generator ismaximum when the near-field light generator is irradiated with theirradiating light.

According to the present invention, the light emitted from the laserdiode element reaches the near-field light generator, and thus thenear-field light generator generates near-field light. Since thenear-field light generator is located in proximity to the magneticrecording element on the medium-facing surface, the temperature rises ina recording region of the magnetic recording medium opposed to themedium-facing surface, to temporarily lower the coercive force of therecording region. The magnetic recording element is energized duringthis period of the lowered coercive force to generate a writing magneticfield and thereby to write information in the recording region.

Furthermore, since the positional relation between the magnetic headportion and the slider substrate is similar to that of the conventionalmagnetic heads, i.e., since the integration surface of the magnetic headportion is parallel to the side faces of the slider substrate andperpendicular to the medium-facing surface, the magnetic recordingelement of the magnetic head portion can be readily formed by theproduction methods of the conventional thin film magnetic heads.

Moreover, the present invention can adequately prevent the insufficientheating of the magnetic recording medium even if the temperature of thelaser diode element rises during the operation of the thermally assistedmagnetic head. Namely, it is known that the laser diode elementdecreases the intensity of emitted light with increase in thetemperature of itself and shifts the wavelength of the emitted light tothe longer wavelength side. In the present invention, the wavelength kinof the emitted light from the laser diode element immediately beforearrival at the near-field light generator is shorter than the wavelengthλmax of the irradiating light to most efficiently generate thenear-field light from the near-field light generator, i.e., thewavelength λmax of the irradiating light capable of generating thenear-field light at the highest intensity upon irradiation of thenear-field light generator with the irradiating light at a constantintensity. This results in shifting the wavelength of the emitted lightfrom the laser diode element to the longer wavelength side and therebyincreasing the efficiency of generation of the near-field light. As aresult, compensation is made for the decease in the intensity of theemitted light from the laser diode element due to the temperature riseand the decrease in the intensity of the near-field light is adequatelyprevented whereby the recording region of the magnetic recording mediumcan be sufficiently heated.

Preferably, the magnetic head portion further has a core of a planarwaveguide including a light exit face on which the near-field lightgenerator is formed, and the emitted light from the laser diode elementis incident to a light entrance face of the planar waveguide. Thisconfiguration causes the emitted light from the laser diode element toenter the light entrance face of the planar waveguide, so that theemitted light from the laser diode element can be readily guided to thenear-field light generator.

Preferably, the thermally assisted magnetic head further comprises alight source support substrate having a second surface fixed to thefirst surface of the slider substrate, the light entrance face is formedin a surface opposite to the light exit face, and the laser diodeelement is fixed to the light source support substrate so as to face thelight entrance face.

Since in this configuration the laser diode element is fixed to thelight source support substrate and the first surface of the slidersubstrate is fixed to the second surface of the light source supportsubstrate, the positional relation is fixed between the slider substrateand the laser diode element. Since the laser diode element faces thelight entrance face of the core, there is no long-distance lightpropagation through an optical fiber, a lens, a mirror, or the like,whereby the emitted light from the laser diode element can be guided tothe near-field light generator on the medium-facing surface, whileallowing some mounting error and coupling loss of light, and thestructure is also simplified.

Furthermore, since the laser diode element is located at a positionapart from the medium-facing surface and near the slider, thisconfiguration suppresses the adverse effect of the heat generated fromthe laser diode element, on the magnetic recording element and othersand possibilities of contact and the like between the laser diodeelement and the medium.

An HGA according to the present invention preferably comprises theabove-described thermally assisted magnetic head, and a suspensionsupporting the thermally assisted magnetic head. A hard disk driveaccording to the present invention preferably comprises theabove-described HGA, and a magnetic recording medium facing themedium-facing surface.

The hard disk drive with the foregoing HGA is able to adequately reducethe occurrence of the writing failure due to the insufficient heating ofthe magnetic recording medium.

The thermally assisted magnetic head, and the HGA and the hard diskdrive with this thermally assisted magnetic head according to thepresent invention are able to prevent the insufficient heating of therecording medium due to the rise in the temperature of the laser diodeelement in the simple structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a hard disk drive according to anembodiment.

FIG. 2 is a perspective view of an HGA 17.

FIG. 3 is an enlarged perspective view of a part near a thermallyassisted magnetic head 21 shown in FIG. 1.

FIG. 4 is a sectional view of the thermally assisted magnetic head 21shown in FIG. 3, taken along line IV-IV and in the direction of arrows.

FIG. 5 is a circuit diagram of the thermally assisted magnetic head 21.

FIG. 6 is a plan view of a major part of the magnetic head as seen fromthe medium-facing surface side.

FIG. 7 is a perspective view of a major part of the thermally assistedmagnetic head 21.

FIG. 8 is a perspective view of a near-field light generator (plasmonprobe) 36 as seen from the medium-facing surface S.

FIG. 9 is a graph showing the simulation result of relationship ofwavelength λ (nm) of incident light to the near-field light generator 36against near-field light intensity I (a.u.).

FIG. 10 is a graph showing the simulation result of relationship ofwavelength λ (nm) of incident light to the near-field light generator 36against near-field light intensity I (a.u.).

FIG. 11 is a graph showing the simulation result of relationship ofwavelength λ (nm) of incident light to the near-field light generator 36against near-field light intensity I (a.u.).

FIG. 12 is a graph showing the simulation result of relationship ofwavelength λ (nm) of incident light to the near-field light generator 36against near-field light intensity I (a.u.).

FIG. 13 is a graph showing the simulation result of relationship ofwavelength λ (nm) of incident light to the near-field light generator 36against near-field light intensity I (a.u.).

FIG. 14 is a perspective view of a laser diode 40.

FIG. 15A is a perspective view for explaining an embodiment of a methodof forming the waveguide 35 and near-field light generator 36.

FIG. 15B is a perspective view for explaining an embodiment of a methodof forming the waveguide 35 and near-field light generator 36.

FIG. 15C is a perspective view for explaining an embodiment of a methodof forming the waveguide 35 and near-field light generator 36.

FIG. 15D is a perspective view for explaining an embodiment of a methodof forming the waveguide 35 and near-field light generator 36.

FIG. 16A is a perspective view for explaining the embodiment of themethod of forming the waveguide 35 and near-field light generator 36.

FIG. 16B is a perspective view for explaining the embodiment of themethod of forming the waveguide 35 and near-field light generator 36.

FIG. 16C is a perspective view for explaining the embodiment of themethod of forming the waveguide 35 and near-field light generator 36.

FIG. 17A is a perspective view showing a production method of thethermally assisted magnetic head.

FIG. 17B is a perspective view showing a production method of thethermally assisted magnetic head.

FIG. 18 is a perspective view of near-field generators 36 of “bow tietype” structure.

FIG. 19 is a sectional view of a magnetic head according to amodification of the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments for carrying out the present invention will be describedbelow in detail with reference to the accompanying drawings. In each ofthe drawings, the same elements will be denoted by the same referencenumerals. It is also noted that the dimensional ratios in and betweenthe constituent elements in the drawings are arbitrary, for easierunderstanding of the drawings.

(Hard Disk Drive)

FIG. 1 is a perspective view of a hard disk drive according to anembodiment.

The hard disk drive 1 has magnetic disks 10 consisting of a plurality ofmagnetic recording media to rotate around a rotation shaft of spindlemotor 11, an assembly carriage device 12 for positioning each thermallyassisted magnetic head 21 on a track, and a recording, reproduction, andemission control circuit (control circuit) 13 for controlling writingand reading operations of each thermally assisted magnetic head 21 andfor controlling a laser diode as a light source for emitting laser lightfor thermally assisted magnetic recording, which will be detailed later.

The assembly carriage device 12 is provided with a plurality of drivearms 14. These drive arms 14 are angularly rockable around a pivotbearing shaft 16 by voice coil motor (VCM) 15, and are stacked in thedirection along this shaft 16. A head gimbal assembly (HGA) 17 isattached to the distal end of each drive arm 14. Each HGA 17 is providedwith a thermally assisted magnetic head 21 so that it faces the surfaceof each magnetic disk 10. The surface of the magnetic head 21 facing thesurface of the magnetic disk 10 is a medium-facing surface S (which isalso called an air bearing surface) of the thermally assisted magnetichead 21. The number of each of magnetic disks 10, drive arms 14, HGAs17, and thermally assisted magnetic heads 21 may be one.

(HGA)

FIG. 2 is a perspective view of an HGA 17. In the same drawing themedium-facing surface S of HGA 17 is illustrated up.

The HGA 17 is constructed by fixing the thermally assisted magnetic head21 to a distal end of suspension 20 and electrically connecting one endof wiring member 203 to terminal electrodes of the thermally assistedmagnetic head 21. The suspension 20 is composed mainly of a load beam200, a flexure 201 with elasticity fixed and supported on this load beam200, a tongue portion 204 formed in a plate spring shape at the tip ofthe flexure, a base plate 202 disposed on the base part of the load beam200, and a wiring member 203 disposed on the flexure 201 and consistingof a lead conductor and connection pads electrically connected to theboth ends of the lead conductor.

It is obvious that the structure of the suspension in the HGA 17 is notlimited to the above-described structure. An IC chip for driving of thehead may be mounted midway in the suspension 20, though not shown.

(Thermally Assisted Magnetic Head)

FIG. 3 is an enlarged perspective view of a part near the thermallyassisted magnetic head 21 shown in FIG. 1.

The wiring member 203 has a pair of electrode pads 237, 237 forrecording signal, a pair of electrode pads 238, 238 for readout signal,and a pair of electrode pads 247, 248 for driving of the light source.

The thermally assisted magnetic head 21 has a configuration in which aslider 22, and a light source unit 23 having a light source supportsubstrate 230 and a laser diode (light emitting element) 40 as a lightsource for thermally assisted magnetic recording are bonded and fixed toeach other so that a back surface (first surface) 2201 of a slidersubstrate 220 is in contact with a bond surface (second surface) 2300 ofthe light source support substrate 230. The back surface 2201 of theslider substrate 220 herein is a surface opposite to the medium-facingsurface S of the slider 22. A bottom surface 2301 of the light sourcesupport substrate 230 is bonded to the tongue portion 204 of the flexure201, for example, with an adhesive such as epoxy resin.

The slider 22 has a slider substrate 220, and a magnetic head portion 32for performing writing and reading of data signal.

The slider substrate 220 is of a plate shape and has the medium-facingsurface S processed so as to achieve an appropriate levitation amount.The slider substrate 220 is made of electrically conductive AlTiC(Al₂O₃—TiC) or the like.

The magnetic head portion 32 is formed on an integration surface 2202which is a side surface approximately perpendicular to the medium-facingsurface S of the slider substrate 220. The magnetic head portion 32 hasan MR effect element 33 as a magnetic detecting element for detectingmagnetic information, an electromagnetic coil element 34 as aperpendicular (or, possibly, longitudinal) magnetic recording elementfor writing magnetic information by generation of a magnetic field, awaveguide (core) 35 as a planar waveguide provided through between theMR effect element 33 and the electromagnetic coil element 34, anear-field light generator (plasmon probe) 36 for generating near-fieldlight for heating a recording layer portion of a magnetic disk, and aninsulating layer (cladding) 38 formed on the integration surface 2202 soas to cover these MR effect element 33, electromagnetic coil element 34,core 35, and near-field light generator 36.

Furthermore, the magnetic head portion 32 has a pair of electrode pads371, 371 for signal terminals formed on an exposed surface of theinsulating layer 38 and connected respectively to input and outputterminals of the MR effect element 33, a pair of electrode pads 373, 373for signal terminals connected respectively to the two ends of theelectromagnetic coil element 34, and an electrode pad 375 for groundelectrically connected to the slider substrate 220. The electrode pad375 electrically connected through a via hole 375 a to the slidersubstrate 220 is connected through a bonding wire to the electrode pad247 of the flexure 201 and a potential of the slider substrate 220 iscontrolled, for example, to the ground potential by the electrode pad247.

Each of the end faces of the MR effect element 33, electromagnetic coilelement 34, and near-field light generator 36 is exposed on themedium-facing surface S. The two ends of the laser diode 40 areconnected to the electrode pads 47, 48, respectively.

FIG. 4 is a sectional view of the thermally assisted magnetic head 21shown in FIG. 3, taken along line IV-IV and in the direction of arrows.

The MR effect element 33 includes an MR laminate 332, and a lower shieldlayer 330 and an upper shield layer 334 located at respective positionson both sides of this MR laminate 332. The lower shield layer 330 andthe upper shield layer 334 can be made, for example, of a magneticmaterial of NiFe, CoFeNi, CoFe, FeN, FeZrN, or the like and in thethickness of about 0.5-3 μm by a pattern plating method including aframe plating method, or the like. The upper and lower shield layers 334and 330 prevent the MR laminate 332 from being affected by an externalmagnetic field serving as noise.

The MR laminate 332 includes a magneto-resistance effect film such as anin-plane conduction type (CIP (Current In Plane)) Giant MagnetoResistance (GMR) multilayer film, a perpendicular conduction type (CPP(Current Perpendicular to Plane)) GMR multilayer film, or a TunnelMagneto Resistance (TMR) multilayer film, and is sensitive to a signalmagnetic field from the magnetic disk with very high sensitivity.

For example, when the MR laminate 332 includes a TMR effect multilayerfilm, it has a structure in which the following layers are stacked inorder: an antiferromagnetic layer made of IrMn, PtMn, NiMn, RuRhMn, orthe like and in the thickness of about 5-15 nm; a magnetization fixedlayer comprised, for example, of CoFe or the like as a ferromagneticmaterial, or two layers of CoFe or the like with a nonmagnetic metallayer of Ru or the like in between, and having the magnetizationdirection fixed by the antiferromagnetic layer; a tunnel barrier layerof a nonmagnetic dielectric material made, for example, by oxidizing ametal film of Al, AlCu, or the like about 0.5-1 nm thick by oxygenintroduced into a vacuum chamber, or by native oxidation; and amagnetization free layer comprised, for example, of two layered films ofCoFe or the like about 1 nm thick as a ferromagnetic material and NiFeor the like about 3-4 nm thick, and effecting tunnel exchange couplingthrough the tunnel barrier layer with the magnetization fixed layer.

An interelement shield layer 148 made of the same material as the lowershield layer 330 is formed between the MR effect element 33 and thewaveguide 35. The interelement shield layer 148 performs a function ofshielding the MR effect element 33 from a magnetic field generated bythe electromagnetic coil element 34 and preventing external noise duringreadout. A backing coil portion may also be further formed between theinterelement shield layer 148 and the waveguide 35. The backing coilportion generates a magnetic flux to cancel a magnetic flux loopgenerated by the electromagnetic coil element 34 and passing via theupper and lower electrode layers of the MR effect element 33, andthereby suppresses the Wide Area Track Erasure (WATE) phenomenon beingan unwanted writing or erasing operation on the magnetic disk.

The insulating layer 38 made of alumina or the like is formed betweenthe shield layers 330, 334 on the opposite side to the medium-facingsurface S of the MR laminate 332, on the opposite side to themedium-facing surface S of the shield layers 330, 334, 148, between thelower shield layer 330 and the slider substrate 220, and between theinterelement shield layer 148 and the waveguide 35.

When the MR laminate 332 includes a CIP-GMR multilayer film, upper andlower shield gap layers for insulation of alumina or the like areprovided between each of the upper and lower shield layers 334 and 330,and the MR laminate 332. Furthermore, an MR lead conductor layer forsupplying a sense current to the MR laminate 332 to extract reproductionoutput is formed though not shown. On the other hand, when the MRlaminate 332 includes a CPP-GMR multilayer film or a TMR multilayerfilm, the upper and lower shield layers 334 and 330 also function asupper and lower electrode layers, respectively. In this case, the upperand lower shield gap layers and MR lead conductor layer are unnecessaryand omitted.

A hard bias layer HM (cf. FIG. 7) of a ferromagnetic material such asCoTa, CoCrPt, or CoPt, for applying a vertical bias magnetic field forstabilization of magnetic domains, is formed on each of both sides inthe track width direction of the MR laminate 332.

The electromagnetic coil element 34 is preferably one for perpendicularmagnetic recording and, as shown in FIG. 4, has a main magnetic polelayer 340, a gap layer 341 a, a coil insulating layer 341 b, a coillayer 342, and an auxiliary magnetic pole layer 344.

The main magnetic pole layer 340 is a magnetic guide for guiding amagnetic flux induced by the coil layer 342, up to the recording layerof the magnetic disk (medium) as a target of writing, while convergingthe magnetic flux. The end of the main magnetic pole layer 340 on themedium-facing surface S side preferably has a width in the track widthdirection (depth direction in FIG. 4) and a thickness in the stackdirection (horizontal direction in FIG. 4) smaller than those of theother portions. This results in permitting the main magnetic pole layerto generate a fine and strong writing magnetic field adapted for highrecording density.

The end portion of the auxiliary magnetic pole layer 344 on themedium-facing surface S side, which is magnetically coupled with themain magnetic pole layer 340, forms a trailing shield portion wider in alayer section than the other portion of the auxiliary magnetic polelayer 344. The auxiliary magnetic pole layer 344 is opposed through thegap layer (cladding) 341 a and coil insulating layer 341 b made of aninsulating material such as alumina, to the end of the main magneticpole layer 340 on the medium-facing surface S side. When the auxiliarymagnetic pole layer 344 of this configuration is provided, the magneticfield gradient becomes steeper between the auxiliary magnetic pole layer344 and the main magnetic pole layer 340 near the medium-facing surfaceS. This results in decreasing jitter of signal output and permittingdecrease in the error rate during readout.

The auxiliary magnetic pole layer 344 is made, for example, in thethickness of about 0.5 to about 5 μm and, for example, of an alloy oftwo or three out of Ni, Fe, and Co or an alloy containing these asprincipal ingredients and doped with a predetermined element by frameplating, sputtering, or the like.

The gap layer 341 a separates the coil layer 342 from the main magneticpole layer 340 and is made, for example, in the thickness of about 0.01to about 0.5 μm and, for example, of Al₂O₃ or DLC or the like bysputtering, CVD, or the like.

The coil layer 342 is made, for example, in the thickness of about 0.5to about 3 μm and, for example, of Cu or the like by frame plating orthe like. The rear end of the main magnetic pole layer 340 is coupledwith the portion of the auxiliary magnetic pole layer 344 apart from themedium-facing surface S and the coil layer 342 is formed so as tosurround this coupling portion.

The coil insulating layer 341 b separates the coil layer 342 from theauxiliary magnetic pole layer 344 and is made, for example, in thethickness of about 0.1 to about 5 μm and of an electric insulatingmaterial such as thermally cured alumina or resist layer or the like.

FIG. 5 is a circuit diagram of the thermally assisted magnetic head 21.

One of wires forming the wiring member 203 is electrically connectedthrough the electrode pad 247 and electrode pad 47 to the cathode of thelaser diode 40, and another wire is electrically connected through theelectrode pad 248 and electrode pad 48 to the anode of the laser diode40. The laser diode 40 emits light with supply of a drive currentbetween the electrode pads 247, 248. This light travels through the coreof the planar waveguide and the medium-facing surface S (cf. FIG. 4) toirradiate a recording region R of the magnetic recording medium.

Another pair of wires forming the wiring member 203 are connectedthrough the electrode pads 237, bonding wires BW, and electrode pads 371to the two ends of the electromagnetic coil element 34. When a voltageis applied between the pair of electrode pads 237, an electric currentis fed to the electromagnetic coil element 34 as a magnetic recordingelement to generate a writing magnetic field. In the thermally assistedmagnetic head 21, the light emitted from the laser diode 40 is incidentto a light entrance face 354 of the core 35 of the planar waveguide andemerges from a light exit face thereof provided in the medium-facingsurface S to irradiate the recording region R of the magnetic recordingmedium (cf. FIG. 4). Therefore, the temperature rises in the recordingregion R of the magnetic recording medium facing the medium-facingsurface, to temporarily lower the coercive force of the recording regionR. Information can be written in the recording region R when theelectromagnetic coil element 34 is energized during this period of thelowered coercive force.

Another pair of wires forming the wiring member 203 are connectedthrough the electrode pads 238, bonding wires BW, and electrode pads 373to the two ends of the MR effect element 33, respectively. When avoltage is applied between the pair of electrode pads 238, a sensecurrent flows to the MR effect element 33. Information written in therecording region R can be read out with flow of the sense current to theMR effect element 33.

FIG. 6 is a plan view of a major part of the magnetic head as seen fromthe medium-facing surface side.

The tip of the main magnetic pole layer 340 on the medium-facing surfaceS side is tapered in a shape of such an inverted trapezoid that thelength of the side on the leading side or slider substrate 220 side isshorter than the length of the side on the trailing side.

The end face of the main magnetic pole layer 340 on the medium-facingsurface side is provided with a bevel angle θ, in order to avoidunwanted writing or the like on an adjacent track by influence of a skewangle made by actuation with a rotary actuator. The magnitude of thebevel angle θ is, for example, approximately 15°. In practice, thewriting magnetic field is generated mainly near the longer side on thetrailing side and in the case of the magnetic dominant recording, thelength of this longer side determines the width of the writing track.

Here the main magnetic pole layer 340 is preferably made, for example,in the total thickness of about 0.01 to about 0.5 μm at the end portionon the medium-facing surface S side and in the total thickness of about0.5 to about 3.0 μm at the portions other than this end portion and, forexample, of an alloy of two or three out of Ni, Fe, and Co or an alloycontaining the foregoing elements as main ingredients and doped with apredetermined element by frame plating, sputtering, or the like. Thetrack width can be, for example, 100 nm.

FIG. 7 is a perspective view of a major part of the thermally assistedmagnetic head 21.

When the X-axis is set along the thickness direction of the waveguide(core) 35, the Y-axis along the width direction, and the Z-axis alongthe longitudinal direction, the light emitted along the Z-axis from thelight emitting surface of the laser diode 40 is incident to the lightentrance face 354.

The core 35 is located between the MR effect element 33 and theelectromagnetic coil element 34, extends in parallel with theintegration surface (YZ plane) 2202 (cf. FIG. 4), extends from themedium-facing surface S of the magnetic head portion 32 to the surface32 a opposite to the medium-facing surface S of the magnetic headportion 32, and is of a rectangular plate shape in the present example.The core 35 has two side faces 351 a, 351 b both extending from themedium-facing surface S and opposed in the track width direction, andtwo upper face 352 a and lower face 352 b parallel to the integrationsurface 2202, and the core 35 also has a light exit face 353 forming themedium-facing surface S, and a light entrance face 354 opposite to thelight exit face 353. The upper face 352 a, the lower face 352 b, and thetwo side faces 351 a, 351 b of the waveguide 35 are in contact with theinsulating layer 38 having the refractive index smaller than that of thewaveguide 35 and functioning as a cladding for the waveguide 35.

This waveguide 35 is able to guide light incident through the lightentrance face 354, to the light exit face 353 as the end face on themedium-facing surface S side, while reflecting the light on the two sidefaces 351 a, 351 b, the upper face 352 a, and the lower face 352 b. Thewidth W35 of the core 35 in the track width direction can be, forexample, 1-200 μm, the thickness T35, for example, 2-10 μm, and theheight H35 10-300 μm.

The core 35 is made, for example, by sputtering or the like, from adielectric material which has the refractive index n higher than that ofthe material making the insulating layer 38, everywhere. For example, ina case where the insulating layer 38 as a cladding is made of SiO₂(n=1.5), the core 35 may be made of Al₂O₃ (n=1.63). Furthermore, in acase where the insulating layer 38 is made of Al₂O₃ (n=1.63), the core35 may be made of Ta₂O₅ (n=2.16), Nb₂O₅ (n=2.33), TiO (n=2.3-2.55), orTiO₂ (n=2.3-2.55). When the core 35 is made of one of such materials,the total reflection condition is met at the interface, in addition tothe good optical characteristics of the material itself, so as todecrease the propagation loss of laser light and increase the efficiencyof generation of near-field light.

The near-field light generator 36 is a platelike member disposed nearlyin the center of the light exit face 353 of the waveguide 35. Thenear-field light generator 36 is buried in the light exit face 353 ofthe waveguide 35 so that the end face thereof is exposed in themedium-facing surface S. When the near-field light generator 36 isirradiated with the light from the laser diode 40, it generates thenear-field light. When the near-field light generator 36 is irradiatedwith the light, electrons in the metal making the near-field lightgenerator 36 come to oscillate in a plasma (plasma oscillation) to causeconcentration of the electric field at the distal end. Since a spread ofthis near-field light is approximately equal to the radius of the distalend of the plasmon probe, we can enjoy a pseudo effect of narrowing downthe emitted light to below the diffraction limit if the radius of thedistal end is set to below the track width.

The main magnetic pole layer 340 extends from the helical center of thecoil layer 342 toward the medium-facing surface S. When an electriccurrent is fed to the coil layer 342, a magnetic field is guided throughthe main magnetic pole layer 340 to the medium-facing surface S togenerate the writing magnetic field spreading outwardly from themedium-facing surface S.

The thermally assisted magnetic head 21 described above has the slidersubstrate 220 having the medium-facing surface S, the first surface 2201located on the opposite side to the medium-facing surface S, and theside surfaces located between the medium-facing surface and the firstsurface 2201; the core 35 of the planar waveguide having the light exitface 353 on the medium-facing surface side; the magnetic head portion 32having the magnetic recording element 34 in proximity to the light exitface 353 and fixed to one of the side surfaces of the slider substrate220; the light source support substrate 230 having the second surface2300 fixed to the first surface 2201; and the light emitting element 40facing the light entrance face 354 of the core 35 and fixed to the lightsource support substrate 230 (cf. FIG. 4). The term “proximity” refersto a distance defined as follows: before a recording region R of themagnetic recording medium heated by the light exit face 353 returns toits original temperature, the magnetic field from the magnetic recordingelement 34 can be applied to the heated recording region. The core 35has the constant thickness in the X-axis direction and a quadrangular XYcross section.

Since the laser diode 40 is fixed to the light source support substrate230 and the first surface 2201 of the slider substrate 220 is fixed tothe second surface 2300 of the light source support substrate 230, theslider substrate 220 and the laser diode 40 are kept in a fixedpositional relation. Since the laser diode 40 faces the light entranceface 354 of the core, the long-distance propagation of light as in theconventional technology is avoided, so that the emitted light from thelight emitting element can be guided to the medium-facing surface, whilepermitting some mounting error and coupling loss of light.

FIG. 8 is a perspective view of the near-field light generator (plasmonprobe) 36 as viewed from the medium-facing surface S.

The near-field light generator 36 is of a triangular shape when viewedfrom the medium-facing surface S, and is made of an electroconductivematerial. The base 36 d of the triangle is arranged in parallel with theintegration surface 2202 of the slider substrate 220 or in parallel withthe track width direction, and the vertex 36 c facing the base isarranged on the main magnetic pole layer 340 side of the electromagneticcoil element 34 with respect to the base 36 d; specifically, the vertex36 c is arranged opposite to the leading edge E of the main magneticpole layer 340. A preferred form of the near-field light generator 36 isan isosceles triangle whose two base angles at the two ends of the base36 d are equal to each other.

The radius r of curvature at the vertex 36 c of the near-field lightgenerator 36 is preferably 5-100 nm. The height H36 of the triangle ispreferably sufficiently smaller than the wavelength of incident laserlight and preferably 20-400 nm. The width W of the base 36 d ispreferably sufficiently smaller than the wavelength of incident laserlight and preferably 20-400 nm. The angle β of the vertex 36 c is, forexample, 60°.

The thickness T36 of the near-field light generator 36 is preferably10-100 nm.

When the near-field light generator 36 is disposed on the light exitface 353 of the core 35, the electric field is concentrated near thevertex 36 c of the near-field light generator 36 and the near-fieldlight is generated from near the vertex 36 c toward the medium.

The near-field light generally has the maximum intensity at the borderof the near-field light generator 36 when viewed from the medium-facingsurface S, though it depends upon the wavelength of the incident laserlight and the shape of the core 35. Particularly, the present embodimentis so arranged that the electric field vector of the light arriving atthe near-field light generator 36 is directed in the stack direction(X-direction) of the laser diode 40. Therefore, radiation of thestrongest near-field light occurs near the vertex 36 c. Namely, the partfacing the vicinity of this vertex 36 c becomes a major heat-actingportion in the thermal assist action to heat a portion of the recordinglayer of the magnetic disk with light.

Since the electric field intensity of this near-field light isimmeasurably stronger than that of the incident light, this very strongnear-field light rapidly heats the opposed local part of the surface ofthe magnetic disk. This reduces the coercive force of this local part toa level allowing writing with the writing magnetic field, wherebywriting with the electromagnetic coil element 34 becomes feasible evenwith use of the magnetic disk of a high coercive force for high-densityrecording. The near-field light penetrates to the depth of about 10-30nm from the medium-facing surface S toward the surface of the magneticdisk. Therefore, under the present circumstances where the levitationamount is 10 nm or less, the near-field light can reach the recordinglayer part sufficiently. The width in the track width direction and thewidth in the medium-moving direction of the near-field light generatedin this manner are approximately equal to the aforementioned reach depthof the near-field light, and the electric field intensity of thisnear-field light exponentially decreases with increase in the distance;therefore, the near-field light can heat the recording layer part of themagnetic disk in an extremely localized area.

FIGS. 9 to 13 are the results of simulation of relationship betweenwavelength λ (nm) of incident light to the near-field light generator 36and intensity I (a.u.) of near-field light. As a condition for thesimulation, the angle β at the vertex 36 c of the near-field lightgenerator 36 was 60°. The material of the near-field light generator 36in each sample was Al, Cu, Ag, Au, or Au in the order of FIGS. 9 to 13.The height H36 was 100 nm in all the samples of FIGS. 9 to 12, and was200 nm in the sample of FIG. 13.

As shown in FIGS. 9 to 13, it is understood that the intensity ofnear-field light has a peak value at a specific wavelength of incidentlight. It is seen from the results of FIGS. 9 to 12 that even in thesame shape of the near-field light generator 36, the wavelength ofincident light at the peak of intensity of near-field light differsdepending upon kinds of the metal material forming the near-field lightgenerator 36. Specifically, where the length H36 of the near-field lightgenerator 36 is 100 nm, the wavelength of incident light at the maximumintensity of near-field light is 390 nm, 640 nm, 560 nm, or 630 nm inthe order of Al, Cu, Ag, or Au, respectively, as the metal materialforming the near-field light generator 36.

It is also found from the results of FIGS. 12 and 13 that with the samemetal material forming the near-field light generator 36, the wavelengthof incident light at the peak of intensity of near-field light differsdepending upon the shapes of the near-field light generator 36.Specifically, where the metal material forming the near-field lightgenerator 36 is Au, the wavelength of incident light at the maximumintensity of near-field light is 630 nm or 830 nm in the order of 100 nmor 200 nm, respectively, as the length H36 of the near-field lightgenerator 36.

As apparent from this simulation result, the wavelength of incidentlight at the peak of intensity of near-field light can be determined ina wide range by properly selecting the shape and metal material of thenear-field light generator 36. In the present embodiment, then, theshape and metal material of the near-field light generator 36, the typeof the laser diode 40, and others are selected so as to satisfy therelation of λin<λmax, where λin is the wavelength of the emitted lightfrom the laser diode 40 immediately before the emitted light reaches thenear-field light generator 36 and λmax is the wavelength of irradiatinglight capable of generating the near-field light at the highestintensity when the near-field light generator 36 is irradiated with theirradiating light at a constant intensity (i.e., the wavelength ofirradiating light at which the efficiency of generation of near-fieldlight from the near-field light generator 36 is maximum when it isirradiated with the irradiating light). For example, in the case wherethe near-field light generator 36 is one of the shape and material underthe simulation condition shown in FIG. 9, the value of λin is set toless than 390 nm, preferably, 300-390 nm.

The wavelength λin immediately before the emitted light from the laserdiode 40 reaches the near-field light generator 36 is a value obtainedby dividing the value of wavelength λ_(L) of the emitted lightimmediately after emission from the laser diode 40, by a value of therefractive index n of the material forming the core 35, in the presentembodiment. Namely, λin=λ_(L)/n.

As described above, by selecting the shape and metal material of thenear-field light generator 36 and the type of the laser diode 40, it isfeasible to adequately prevent the reduction in the intensity ofnear-field light even if the temperature of the laser diode 40 increasesto decrease the intensity of the emitted light thereof during executionof thermally assisted magnetic recording. Namely, a laser diodegenerally decreases the intensity of its emitted light and shifts thewavelength of the emitted light to the longer wavelength side withincrease in the temperature of the element. In the present embodiment,therefore, the wavelength of emitted light is shifted to the longerwavelength side so as to increase the efficiency of generation ofnear-field light even if the intensity is decreased of the emitted lightfrom the laser diode 40. As a result, the reduction in the intensity ofemitted light from the laser diode 40 is compensated for by the increasein the efficiency of generation of near-field light from the near-fieldlight generator 36, whereby the reduction in the intensity of near-fieldlight can be adequately prevented. Then the recording region R of themagnetic recording medium is fully heated to decrease the coercive forcethereof sufficiently, whereby occurrence of writing failure can beadequately prevented.

The prevention of the reduction in the intensity of near-field light canalso be achieved by placing a temperature detector near the laser diode40 and adjusting the intensity of emitted light by feeding the detectionresult back to the power supply unit of the laser diode 40 on the basisof measured temperature. However, when this method is employed, theapparatus configuration becomes complicated and the yield in productioncan decrease. In contrast to it, the present embodiment can achieve theeffect equivalent to that by the adjustment of intensity of emittedlight from the laser diode 40, simply by properly selecting the shapeand metal material of the near-field light generator 36, the type of thelaser diode 40, and the material forming the core 35, without need forprovision of a special member such as the temperature detector. For thisreason, the apparatus configuration is not complicated and the problemof decrease in the yield in production does not arise.

(Light Source Unit)

The components of the light source unit 23 in the thermally assistedmagnetic head 21 will be described below again with reference to FIGS. 3and 4.

The light source unit 23 mainly has a light source support substrate 230and a laser diode (light emitting element) 40 whose contour isplatelike.

The light source support substrate 230 is a substrate of AlTiC(Al₂O₃—TiC) or the like and has the bond surface 2300 bonded to the backsurface 2201 of the slider substrate 220. A heat insulation layer 230 aof alumina or the like is formed on the bond surface 2300. An insulatinglayer 41 of an insulating material such as alumina is disposed on anelement forming surface 2302 being one side surface when the bondsurface 2300 is regarded as a bottom surface. The electrode pads 47, 48are formed on this insulating layer 41, and the laser diode 40 is fixedon the electrode pad 47.

The electrode pads 47, 48 are formed for driving of laser, on a surface411 intersecting with the front surface of the insulating layer 41 andwith the medium-facing surface S and, in other words, they are formed onthe surface 411 parallel to the integration surface 2202 of the slidersubstrate 220.

The electrode pad 47, as shown in FIG. 4, is electrically connectedthrough a via hole 47 a provided in the insulating layer 41, to thelight source support substrate 230. The electrode pad 47 also functionsas a heat sink for leading heat during driving of the laser diode 40through the via hole 47 a to the light source support substrate 230side.

The electrode pad 47, as shown in FIG. 3, is formed so as to extend inthe track width direction in the central region of the surface 411 ofthe insulating layer 41. On the other hand, the electrode pad 48 isformed at a position separate in the track width direction from theelectrode pad 47. Each of the electrode pads 47, 48 further extendstoward the flexure 201 side, for connection with the flexure 201 bysolder reflow.

The electrode pads 47, 48 are electrically connected to the electrodepads 247, 248 of the flexure 201, respectively, by reflow soldering,whereby the light source can be driven. Since the electrode pad 47 iselectrically connected to the light source support substrate 230 asdescribed above, the potential of the light source support substrate 230can be controlled, for example, to the ground potential by the electrodepad 247.

The electrode pads 47, 48 can be comprised, for example, of layers ofAu, Cu, or the like made in the thickness of about 1-3 μm and by vacuumevaporation, sputtering, or the like, which are formed, for example,through a ground layer of Ta, Ti, or the like about 10 nm thick.

The laser diode 40 is electrically connected onto the electrode pad 47by a solder layer 42 (cf. FIG. 4) of an electrically conductive soldermaterial such as Au—Sn. At this time, the laser diode 40 is locatedrelative to the electrode pad 47 so as to cover only a part of theelectrode pad 47.

FIG. 14 is a perspective view of the laser diode 40.

The laser diode 40 may have the same structure as the one normally usedfor an optical disk storage, and, for example, has a structure in whichthe following layers are stacked in order: an n-electrode 40 a; ann-GaAs substrate 40 b; an n-InGaAlP cladding layer 40 c; a first InGaAlPguide layer 40 d; an active layer 40 e consisting of multiple quantumwells (InGaP/InGaAlP) or the like; a second InGaAlP guide layer 40 f; ap-InGaAlP cladding layer 40 g; an *n-GaAs current blocking layer 40 h; ap-GaAs contact layer 40 i; a p-electrode 40 j. Reflecting films 50 and51 of SiO₂, Al₂O₃, or the like for exciting oscillation by totalreflection are deposited before and after cleavage faces of themultilayer structure, and an aperture is provided at the position of theactive layer 40 e in one reflecting film 50, at an output end 400 foremission of laser light. The laser diode 40 of this configuration emitslaser light from the output end 400 when a voltage is applied thereto inthe film thickness direction.

Concerning the wavelength λ_(L) of the emitted laser light, the laserdiode to emit the laser light of the appropriate wavelength λ_(L), isselected in consideration of the shape and metal material of thenear-field light generator 36 and the refractive index n of the materialforming the core 35, as described above. Namely, the relation ofλin<λmax is satisfied, where λin is the wavelength of the emitted lightfrom the laser diode 40 immediately before it reaches the near-fieldlight generator 36, and λmax is the wavelength of irradiating lightcapable of generating the near-field light at the highest intensity whenthe near-field light generator 36 is irradiated with the irradiatinglight at a constant intensity.

The size of the laser diode 40 is, for example, the width (W40) of200-350 μm, the length (depth L40) of 250-600 μm, and the thickness(T40) of about 60-200 μm, as described above. The width W40 of the laserdiode 40 can be decreased, for example, to about 100 μm, while theminimum thereof is a spacing between opposed ends of the currentblocking layer 40 h. However, the length of the laser diode 40 is thequantity associated with the electric current density and thus cannot bedecreased so much. In either case, the laser diode 40 is preferablydimensioned in a sufficient size, in consideration of handling duringmounting.

A power supply in the hard disk drive can be used for driving of thislaser diode 40. In practice, the hard disk drive is usually equipped,for example, with the power supply of about 2 V, which is a sufficientvoltage for the lasing operation. The power consumption of the laserdiode 40 is also, for example, approximately several ten mW, which thepower supply in the hard disk drive can fully provide.

The n-electrode 40 a of the laser diode 40 is fixed to the electrode pad47 by the solder layer 42 such as AuSn (cf. FIG. 4). The laser diode 40is fixed to the light source support substrate 230 so that the outputend (light emission face) 400 of the laser diode 40 is directed downward(in the −Z-direction) in FIG. 4, i.e., so that the output end 400becomes parallel to the bond surface 2300; whereby the output end 400can face the light entrance face 354 of the waveguide 35 of the slider22. In practical fixing of the laser diode 40, for example, anevaporated film of AuSn alloy is deposited in the thickness of about0.7-1 μm on the surface of the electrode pad 47, the laser diode 40 ismounted thereon, and thereafter it is heated to be fixed, to about200-300° C. by a hot plate or the like under a hot air blower.

The electrode pad 48 is electrically connected through a bonding wire tothe p-electrode 40 j of the laser diode 40. It is also possible to adopta connection method not using the bonding wire, in which the insulatinglayer 41 is provided with a level difference to decrease the distancebetween the electrode pad 48 and the p-electrode 40 j of the laser diode40 and these are electrically connected by a solder such as AuSn. Theelectrode connected to the electrode pad 47 may also be the p-electrode40 j, instead of the n-electrode 40 a, and in this case, the n-electrode40 a is connected through a bonding wire to the electrode pad 48.

In the case of soldering with the aforementioned AuSn alloy, the lightsource unit is heated, for example, to the high temperature of about300° C., but according to the present invention, this light source unit23 is produced separately from the slider 22; therefore, the magnetichead portion in the slider is prevented from being adversely affected bythis high temperature.

The back surface 2201 of the aforementioned slider 22 and the bondsurface 2300 of the light source unit 23 are bonded, for example, withan adhesive layer 44 such as a UV cure type adhesive (cf. FIG. 4) andthe output end 400 of the laser diode 40 is arranged opposite to thelight entrance face 354 of the waveguide 35.

The configurations of the laser diode 40 and the electrode pads do notalways have to be limited to those in the above-described embodiment, ofcourse, and, for example, the laser diode 40 may be one of anotherconfiguration using other semiconductor materials, such as GaAlAs typematerials. Furthermore, it is also possible to use any other brazingmaterial, for the soldering between the laser diode 40 and theelectrodes. Yet furthermore, the laser diode 40 may be formed directlyon the unit substrate by epitaxially growing the semiconductormaterials.

(Production Method)

Subsequently, a method of producing the thermally assisted magnetic headdescribed above will be described below briefly.

First, the slider 22 is produced. Specifically, the slider substrate 220is prepared, the MR effect element 33 and interelement shield layer 148are formed by well-known methods, and the insulating layer 38 of aluminaor the like is further formed as a ground layer.

Subsequently, the waveguide 35 and near-field light generator 36 areformed. This process will be described in detail with reference to FIGS.15 and 16.

FIGS. 15 and 16 are perspective views to illustrate an embodiment of themethod of forming the waveguide 35 and the near-field light generator36.

In the first step, as shown in FIG. 15A, a dielectric film 35 a of Ta₂O₅or the like with the refractive index higher than that of the insulatinglayer 38 a, which will be a part of the waveguide 35, is first depositedon the insulating layer 38 a of Al₂O₃ or the like, a metal layer 36 a ofAu or the like is then deposited thereon, and a resist pattern 1002depressed for liftoff in the bottom part is formed thereon.

In the next step, as shown in FIG. 15B, unnecessary portions of themetal layer 36 a are removed except immediately below the resist pattern1002 by ion milling or the like, thereby forming a pattern of the metallayer 36 a of a trapezoid shape wider in the bottom as deposited on thedielectric film 35 a.

In the subsequent step, as shown in FIG. 15C, the resist pattern 1002 isremoved, and a part of each slope is removed from the two slope sides ofthe metal layer 36 a of the trapezoid shape by ion milling or the like,to form the metal layer 36 a in a triangular sectional shape.

Subsequently, as shown in FIG. 15D, a dielectric film 35 b of the samematerial as the dielectric film 35 a is deposited on the dielectric film35 a so as to cover the metal layer 36 a, a resist pattern 1003 forformation of the end face of the metal layer 36 a is laid on the sidewhere the medium-facing surface will be formed, the metal layer 36 a andthe dielectric film 35 b are removed by ion milling or the like, fromthe side opposite to the side where the medium-facing surface will beformed, as shown in FIG. 16A, and thereafter a dielectric film 35 c ofthe same material as the dielectric film 35 b is deposited on theremoved portion.

Furthermore, as shown in FIG. 16B, a dielectric film 35 d of the samematerial as the dielectric film 35 b is further deposited on thedielectric films 35 b, 35 c, and the dielectric films 35 a, 35 b, 35 c,35 d are patterned so as to achieve a predetermined width, therebyalmost completing the waveguide 35.

Thereafter, as shown in FIG. 16C, an insulating layer 38 b of the samematerial as the insulating layer 38 a is further formed so as to coverthe waveguide 35, thereby completing the insulating layer 38 as acladding layer. Then lapping is performed by a predetermined distancefrom the side where the metal layer 36 a is exposed, as described later,to form the near-field light generator 36 of the predetermined thicknessand the medium-facing surface S.

The above steps can form the waveguide 35 with the near-field lightgenerator 36.

After that, the electromagnetic coil element 34 is formed by thewell-known method as shown in FIG. 4, and then the insulating layer 38of alumina or the like is formed. Furthermore, the electrode pads 371and others for connection are formed and thereafter lapping of the airbearing surface and the back surface thereof is performed to completethe slider 22. After this step, tests of the electromagnetic coilelement 34 and the MR effect element 33 of slider 22 are conducted foreach slider, to select a nondefective product.

Subsequently, the light source unit 23 is produced. In the first step,as shown in FIG. 4, the light source support substrate 230 of AlTiC orthe like is prepared, the heat insulation layer 230 a, insulating layer41, and electrode pads 47, 48 are formed on the surfaces of thesubstrate by well-known methods, the laser diode 40 is fixed on theelectrode pad 47 by an electrically conductive solder material such asAuSn, and thereafter the substrate is shaped into a predetermined sizeby separation by cutting or the like. This completes the light sourceunit 23. The light source unit obtained in this manner is also subjectedto characteristic evaluation of the laser diode, particularly,observation of a profile of drive current by a high-temperaturecontinuous conduction test, to select one considered to have asufficiently long life.

After that, as shown in FIG. 17A, a UV cure type adhesive 44 a isapplied onto either or both of the bond surface 2300 of the light sourceunit 23 as a nondefective unit and the back surface 2201 of the slider22 as a nondefective unit. The UV cure type adhesive can be a UV curetype epoxy resin, a UV cure type acrylic resin, or the like.

Then, as shown in FIG. 17B, the bond surface 2300 of the light sourceunit 23 and the back surface 2201 of the slider 22 are laid on eachother, and then the laser diode 40 is activated with application of avoltage between the electrode pads 47, 48, and a photodetector DT isopposed to the light exit face 353 of the waveguide 35. The light sourceunit 23 and the slider 22 are relatively moved in directions of arrowsin FIG. 17B to find out a position where the output from thephotodetector DT becomes maximum. At that position, UV light is appliedfrom the outside onto the UV cure type adhesive to cure the UV cure typeadhesive 44 a, which can bond the light source unit 23 and the slider 22to each other in a state in which the optical axis of the laser diode isaligned with the optical axis of the waveguide 35.

Subsequently, the action of the thermally assisted magnetic head 21according to the present embodiment will be described below.

During a writing or reading operation, the thermally assisted magnetichead 21 hydromechanically floats up by a predetermined levitation amountabove the surface of the rotating magnetic disk (medium) 10. On thisoccasion, the ends on the medium-facing surface S side of the MR effectelement 33 and the electromagnetic coil element 34 are opposed through asmall spacing to the magnetic disk 10, thereby implementing readout bysensing of a data signal magnetic field and writing by application of adata signal magnetic field.

On the occasion of writing of a data signal, the laser light havingpropagated from the light source unit 23 through the core 35 reaches thenear-field light generator 36, whereupon the near-field light generator36 generates the near-field light. This near-field light enablesexecution of the thermally assisted magnetic recording.

By adopting the thermally assisted magnetic recording, it also becomesfeasible to achieve, for example, the recording density of 1 Tbits/in²order, by performing writing on the magnetic disk of a high coerciveforce by means of the thin film magnetic head for perpendicular magneticrecording to record recording bits in an extremely fine size.

The present embodiment uses the light source unit 23, so that the laserlight propagating in the direction parallel to the layer surface of thecore 35 can be made incident to the light entrance face (end face) 354of the core 35 of the slider 22. Namely, the laser light of appropriatesize and direction can be surely supplied in the thermally assistedmagnetic head 21 having the configuration in which the integrationsurface 2202 and the medium-facing surface S are perpendicular to eachother. As a result, it is feasible to implement the thermally assistedmagnetic recording with high heating efficiency of the recording layerof the magnetic disk.

Since in the present embodiment the magnetic head portion 32 is fixed tothe slider substrate 220 and the laser diode 40 as the light source isseparately fixed to the light source support substrate 230, thethermally assisted magnetic head 21 as a nondefective product can beproduced with a good yield by individually testing each of theelectromagnetic coil element 34 fixed to the slider substrate 220 andthe laser diode 40 fixed to the light source support substrate 230, andthereafter fixing the slider 22 as a nondefective unit and the lightsource unit 23 as a nondefective unit to each other.

Since the magnetic head portion 32 is disposed on the side surface ofthe slider substrate 220, the electromagnetic coil element 34, the MReffect element 33, and others of the magnetic head portion 32 can bereadily formed by the production methods of the conventional thin filmmagnetic heads.

Furthermore, since the laser diode 40 is located at the position apartfrom the medium-facing surface S and near the slider 22, it is feasibleto suppress the adverse effect of the heat generated from the laserdiode 40, on the electromagnetic coil element 34, the MR effect element33, etc., and the possibilities of contact or the like between the laserdiode 40 and the magnetic disk 10, to reduce the propagation loss oflight because of the dispensability of an optical fiber, a lens, amirror, etc., and to simplify the structure of the entire magneticrecording apparatus.

Since in the present embodiment the heat insulation layer 230 a isformed on the back surface of the light source support substrate 230,the heat generated from the laser diode 40 is less likely to betransferred to the slider 22.

In the above embodiment the slider substrate 220 and the light sourcesupport substrate 230 were the substrates of the same material of AlTiC,but it is also possible to use substrates of different materials. Inthis case, where the thermal conductivity of the slider substrate 220 isλs and the thermal conductivity of the light source support substrate230 is λl, they are preferably selected to satisfy λs≦λl. Thisfacilitates the transfer of the heat generated by the laser diode 40,through the light source support substrate 230 to the outside whileminimizing the transfer of the heat to the slider substrate 220.

The sizes of the slider 22 and the light source unit 23 are arbitrary,but the slider 22 may be, for example, a so-called femtoslider havingthe width of 700 μm in the track width direction×length (depth) of 850μm×thickness of 230 μm. In this case, the light source unit 23 can havethe width and length approximately equal to them. In fact, for example,the typical size of the ordinary laser diode is approximately the widthof 250 μm×length (depth) of 350 μm×thickness of 65 μm, and the laserdiode 40 of this size can be adequately mounted, for example, on theside surface of the light source support substrate 230 of this size. Itis also possible to make a groove in the bottom surface of the lightsource support substrate 230 and locate the laser diode 40 in thisgroove.

The spot of the far field pattern (the far field pattern) of the laserlight reaching the light entrance face 354 of the waveguide 35 can bemade in the size in the track width direction, for example, of about0.5-1.0 μm and the size perpendicular to the foregoing size, forexample, of about 1-5 μm. In correspondence thereto, the thickness T35of the waveguide 35 receiving this laser light is preferably, forexample, about 2-10 μm so as to be larger than the spot and the width(W35) in the track width direction of the waveguide 35 is preferably,for example, about 1-200 μm.

The electromagnetic coil element 34 may be one for longitudinal magneticrecording. In this case, a lower magnetic pole layer and an uppermagnetic pole layer are provided instead of the main magnetic pole layer340 and the auxiliary magnetic pole layer 344, and a writing gap layeris interposed between the ends on the medium-facing surface S side ofthe lower magnetic pole layer and the upper magnetic pole layer. Writingis implemented by a leakage magnetic field from the position of thiswriting gap layer.

The shape of the near-field light generator is not limited to the onedescribed above, either, and it can also be, for example, a trapezoidshape resulting from truncation of the vertex 36 c, instead of thetriangular shape. It is also possible to adopt a so-called “bow tietype” structure in which a pair of sheets of a triangular shape or atrapezoidal shape are opposed to each other with their vertices orshorter sides being spaced by a predetermined distance.

FIG. 18 is a perspective view of near-field light generators 36 of the“bow tie type” structure. A pair of near-field light generators arearranged opposite to each other along the X-axis and their vertices 36 care opposed to each other with a predetermined spacing in between. Inthis “bow tie type” structure, a very strong electric field isconcentrated in the central region between the vertices 36 c to generatenear-field light.

It is also possible to adopt a configuration without the light sourcesupport substrate 230. A specific example of that case is shown in FIG.19.

FIG. 19 is a sectional view of a magnetic head according to amodification example of the aforementioned embodiment and corresponds toFIG. 4 in the aforementioned embodiment. This magnetic head 21 a is notprovided with the light source support substrate 230, different fromthat in the aforementioned embodiment. Among the insulating layers(claddings) 38 provided on both sides in the X-direction of core 35, theZ-directional height of the one 38 a located in the −X-direction withrespect to the core 35 is lower than in the aforementioned embodiment. Adiffraction grating portion 35 a is provided on a side face of theZ-directional end of the core 35. A mirror portion 39 is provided on theupper part of the insulating layer 38 a.

In this magnetic head 21 a, emitted light 60 from the laser diode 40travels from the X-direction in the −X-direction in FIG. 19, isreflected by the mirror portion 39, and then is incident to a lightentrance face 354 a of the diffraction grating portion 35 a. Thediffraction grating 35 a has the effect of bending the light incident tothe light entrance face 354 a, into the −Z-direction in FIG. 19, wherebythe emitted light 60 from the laser diode is guided into the core 35. Inthis case, the laser diode can be located, for example, on the uppersurface of HGA 17, drive arm 14, or pivot bearing shaft 16 in FIG. 1.This configuration can also achieve the effect of the present invention.

It is also possible to adopt a configuration without the core 35,wherein a transparent portion of a transparent material forsubstantially transmitting the emitted light from the laser diode isprovided in the core part in the magnetic head portion 32 and whereinthe emitted light is focused by a lens or the like to travel through thetransparent portion and irradiate the near-field light generator 36.

The coil layer 342 is one layer in FIG. 4 and others, but it may be twoor more layers, or a helical coil.

The heat insulation layer 230 a may be formed on the back surface 2201of the slider substrate 220, and the present invention can also becarried out without the heat insulation layer.

The bonding between the light source unit 23 and the slider 22 can alsobe implemented with any adhesive other than the UV cure type adhesive,e.g., with a solder layer of AuSn or the like which was used in thebonding between the laser diode 40 and the electrode pad 47.

In the above-described example the linear waveguide was used as theshape of the core 35, but it may also be a parabolic waveguide whosecontour in the YZ plane is a parabola, while the near-field lightgenerator is located at the position of its focus. The contour in the YZplane may also be an elliptical or other shape. The above-describedthermally assisted magnetic head and hard disk drive with the HGA areable to prevent the insufficient heating of the recording medium even ifthe intensity of the emitted light is lowered due to the rise in thetemperature of the laser diode element during the recording operation.

It should be noted that the above-described embodiments all weredescribed as illustrative of the present invention but not restrictiveof the invention, and that the present invention can also be carried outin a variety of other modification and change forms. Therefore, thescope of the present invention should be defined by the scope of claimsand scope of equivalents thereof only.

1. A thermally assisted magnetic head comprising: a slider substratehaving a medium-facing surface, a first surface located opposite to themedium-facing surface, and side surfaces located between themedium-facing surface and the first surface; a magnetic head portionhaving a near-field light generator on the medium-facing surface side,and a magnetic recording element located in proximity to the near-fieldlight generator, the magnetic head portion being fixed to one of theside surfaces of the slider substrate; and a laser diode element arelative position of which to the slider substrate is fixed so thatemitted light thereof can reach the near-field light generator; whereina relation of λin<λmax is satisfied, where λin is a wavelength of theemitted light from the laser diode element immediately before theemitted light reaches the near-field light generator, and λmax is awavelength of irradiating light at which an efficiency of generation ofnear-field light generated from the near-field light generator ismaximum when the near-field light generator is irradiated with theirradiating light.
 2. The thermally assisted magnetic head according toclaim 1, wherein the magnetic head portion further has a core of aplanar waveguide including a light exit face on which the near-fieldlight generator is formed, and wherein the emitted light from the laserdiode element is incident to a light entrance face of the planarwaveguide.
 3. The thermally assisted magnetic head according to claim 2,further comprising a light source support substrate having a secondsurface fixed to the first surface of the slider substrate, wherein thelight entrance face is formed in a surface opposite to the light exitface, and wherein the laser diode element is fixed to the light sourcesupport substrate so as to face the light entrance face.
 4. A headgimbal assembly comprising: the thermally assisted magnetic head asdefined in claims 1; and a suspension supporting the thermally assistedmagnetic head.
 5. A hard disk drive comprising: the head gimbal assemblyas defined in claim 4; and a magnetic recording medium facing themedium-facing surface.